Recent deployments of Wireless Local Area Networking (WLAN) have layered mobility providing tunnels over the top of the Internet Protocol (IP) to deliver ubiquitous wide-area mobility. GPRS Tunneling Protocol (GTP), Mobile IP (MIP), Proxy Mobile IP (PMIP), WiMAX's R6 Protocol (GRE), all provide mobility services by tunneling packets over the Internet. Notably Mobile IPv6 does have an optional optimized routed mode whereby after having originally traversed a tunnel, packets are subsequently routed directly between the mobile node and its correspondent. However, the control of route optimization is under the control of the tunnel endpoint, and it is anticipated that in reality optimal routing will not be enabled, either because of business, regulatory or technical reasons. Indeed, 3GPP's latest “flat all-IP” architecture termed System Architecture Evolution (SAE) defines support for MIPv6, but uses a combination of GTP and PMIP tunneling to ensure that all users' packets are tunneled back to complex Mobile Gateways where additional services may be applied.
With almost 1 billion mobile phones sold in 2006, the industry will soon be faced with the situation that the default technique for accessing the Internet will be via a mobility tunnel. Such tunneled traffic bypasses the increasing number of value added features being embedded into the fabric of the Internet, for example, enhanced security functionality being integrated into the edge of the access network. The tunneling of traffic brings a mindset of large Telco-type deployments with rigorous requirements on service availability as the state of potentially millions of hosts is centralized in the tunnel gateway. Because of these approaches, “mobile Internet” services will continue to be more brittle than those delivered over the native IP network on top of which the mobility tunnels are transported.